La importancia de garantizar la calidad y minimizar los riesgos de contaminación en el análisis genético forense / The importance of ensuring quality and minimising the risks of contamination in genetics forensic analysis

La alta sensibilidad conseguida en los análisis genéticos de interés forense permite obtener perfiles genéticos procedentes de mínimas trazas de material biológico depositado sobre los indicios, antes o incluso después de los hechos investigados. La contaminación de los indicios biológicos de manera accidental y la interpretación errónea de los resultados genéticos tienen importantes consecuencias con la consiguiente repercusión en el proceso judicial. Minimizar y detectar la presencia de contaminaciones accidentales que se pueden generar durante algunas de las fases de recogida o análisis genético es una prioridad para los laboratorios de análisis genéticos. El presente artículo revisa el marco normativo, así como los estándares de calidad nacionales e internacionales aplicables al ámbito de la genética forense que tienen como objetivo garantizar la calidad de la prueba pericial y la fiabilidad de las conclusiones emitidas en los informes periciales (AU)

The high sensitivity achieved in genetic analysis of forensic interest allows to obtain genetic profiles from minimal traces of biological material deposited on the evidence before or even subsequent to the events under investigation. Accidental contamination of biological evidence and erroneous interpretation of genetic findings have important implications with the consequent impact on the judicial process. Minimising and detecting the presence of accidental contamination that may be generated during some phases of collection of samples or genetic analysis are a priority for forensic genetics laboratories. This article reviews legislation and national and international standards applicable to field of forensic genetics, which aim to ensure the quality of expert evidence and the reliability of the conclusions reached in the expert reports (AU)

Mitochondrial DNA error prophylaxis: assessing the causes of errors in the GEP'02-03 proficiency testing trial.

We report the results of the Spanish and Portuguese working group (GEP) of the International Society for Forensic Genetics (ISFG) Collaborative Exercise 2002-2003 on mitochondrial DNA (mtDNA) analysis. Six different samples were submitted to the participating laboratories: four blood stains (M1-M2-M3-M4), one mixture blood sample (M5), and two hair shaft fragments (M6). Most of the labs reported consensus results for the blood stains, slightly improving the results of previous collaborative exercises. Although hair shaft analysis is still carried out by a small number of laboratories, this analysis yielded a high rate of success. On the contrary, the analysis of the mixture blood stain (M5) yielded a lower rate of success; in spite of this, the whole results on M5 typing demonstrated the suitability of mtDNA analysis in mixture samples. We have found that edition errors are among the most common mistakes reported by the different labs. In addition, we have detected contamination events as well as other minor problems, i.e. lack of standarization in nomenclature for punctual and length heteroplasmies, and indels. In the present edition of the GEP-ISFG exercise we have paid special attention to the visual phylogenetic inspection for detecting common sequencing errors.